Interest in three dimensional (3D) cameras is increasing as the popularity of 3D applications continues to grow in applications such as imaging, movies, games, computers, user interfaces, and the like. A typical passive way to create 3D images is to use multiple cameras to capture stereo or multiple images. Using the stereo images, objects in the images can be triangulated to create the 3D image. One disadvantage with this triangulation technique is that it is difficult to create 3D images using small devices because there must be a minimum separation distance between each camera in order to create the three dimensional images. In addition, this technique is complex and therefore requires significant computer processing power in order to create the 3D images in real time.
For applications that require the acquisition of 3D images in real time, active depth imaging systems based on the optical time of flight measurement are sometimes utilized. Time of flight systems typically employ a light source that directs light at an object and a sensor that detects the light that is reflected from the object. The time between the emission from the light source and the detection of reflected light by the sensor indicates the distance of the object in relation to the sensor. Electronic signals are sent within the time of flight system to coordinate the emission of the light by the light source and the detection of the reflected light by the sensor. However, delays in the electronic signals can compromise the time of flight calculations that indicate the distance of the object from the sensor. Previous approaches to reducing signal delay include reducing the resistance and capacitance of the metal interconnect, however design rules limit the width of the metal interconnect and therefore the achievable resistance value floor (and hence the propagation delay of electronic signals). The use of digital algorithms to calibrate the resultant delayed signal has also been previously used. However, this increases the processing requirements of a time of flight system.